Comprehension matters, but so does pleasure. In Proust and the Squid, Wolf, director of the Center for Reading and Language Research at Tufts University, observes that the brain’s limbic system, the seat of our emotions, comes into play as we learn to read fluently; our feelings of pleasure, disgust, horror and excitement guide our attention to the stories we can’t put down. Novelists have known this for a long time, and digital writers know it, too. It’s no coincidence that many of the best early digital narratives took the form of games, in which the reader traverses an imaginary world while solving puzzles, sometimes fiendishly difficult ones. Considered in terms of cognitive load, these texts are head-bangingly difficult; considered in terms of pleasure, they’re hard to beat.